Another Itinerary/Travel Pass question

You might find that the Half Fare Card saves the most money. The Swiss Travel Pass only gives half off most mountain lifts, same as the Half Fare Card. The exception is the Schilthornbahn to the top, which is now fully covered by the STP.

Yes, either card will give you something off the Swiss portion of Zermatt to Venice. You might also look at buying an advance ticket from Brig to Venice.

You can purchase your ticket Zermatt -> Venezia San Lucia from www.sbb.ch/en and specify that you have some sort of rail pass. Your discounted price will be calculated.

You can also purchase your italian train tix from www.trenitalia.com by searching from Domodossola to Venezia San Lucia. Your Swiss Pass or Half Fare Card will work in Switzerland all the way to Domodossola and from there you'll need a separate ticket onwards.

So either purchase the whole journey via www.sbb.com OR purchase your onwards portation via www.trenitalia.com

Whatever pass you get (Swiss Pass or Half Price Card), if it is valid on the day you travel to Venice, then it is valid to the border station.
See this map: https://www.sbb.ch/content/dam/infrastruktur/trafimage/karten/karte-sts-pass-gueltigkeit.pdf
This is the official map for both passes. Heading from Zermatt to Milan, the border station is Domodossola. Your Swiss Card/Pass will be valid to there, and you need to buy an Italian ticket Domodossola --> Milan --> Venice, which you can buy at the Italian Railways site: http://www.trenitalia.com/tcom-en

Without doing the arithmetic myself, you have 4 days travel, and two "no travel" days (1st and 3rd June). You could get a 4 days in one month pass. But, you probably want to go up mountains on your two days in Mürren and Zermatt. And, Zürich airport to Luztern is a short trip, not worth a pass day. So I concur, the Half Price card is probably the best option.

The webpage with all the passes is here: https://www.sbb.ch/en/leisure-holidays/travel-in-switzerland/international-guests.html

Here is currently the cheapest way to get from Zermatt to Venice on June 4.
Purchase today 2 2nd class SuperEconomy tickets from Domodossola to Venezia S. Lucia departing at 15:17 for 49.60 EUR total. That is EC 57 to Milan connecting to Frecciarossa 9749 to Venice arriving at 20:10. Buy these at http://www.trenitalia.com/tcom-en
Then buy tickets (you can do this at Zermatt station if you have the Half Fare Card, or just get on the train if you have the STP) Zermatt to Domodossola. You will connect with the EC 57 in Brig and board there. At Domodossola you don't have to move, your ticket just switches from the Swiss ticket to the Italian ticket. In fact, the Italian ticket will have seat reservations, so you might as well just take these when you board at Brig.
The cost for 2 with the HFC is 28.30 CHF. So the equivalent total price for 2 is 74 EUR or 87 CHF.

You can do the same 1 hour later for the EC 39 to the Frecciarosa 9751, arriving only 30 minutes later.

Cost is 20.40 EUR total if you want the morning EC 37 direct to Venice. Swiss trains are always the same price. Italian SuperEconomy tickets are like airline tickets, good only for that train on that date. Miss it and throw the ticket away and start over.

You can also buy the whole package from SBB, the Swiss railway, but it is 210 CHF for 2 with the HFC, or 156 CHF with a STP.

Thank you all for the replies. This is very helpful information, although overwhelming as well.

I should also add that my fiance is under 26, so she'll be able to use a Youth ticket on all the trains that we take. Which obviously cuts down the cost too.

Any suggestions on what to do in Zermatt if the weather is not so great? Is there any sort of night life in the town? I know there are plenty of walking/hiking trails in the area, which is definitely something that we'll be doing. I also know that one of the main lifts (can't remember which one) will still be closed at the time of our visit, so we'd also be looking for suggestions on which lift to take in order to get some great Matterhorn views.

Maybe the Glacier Palace is a cloudy day option?
https://www.zermatt.ch/en/Media/Attractions/Glacier-palace
The only lifts not running when you are there are secondary lifts to Schwarzsee, Riffelberg. The Gornergratbahn and trams to Trockner Steg and Klein Matterhorn (Glacier Palace) and the Furggsattel chairlift (skiing) will be running.

The reduction for under 26 is a benefit, but not earthshaking, 58 CHF on an 8-day Travel Pass. There is no substitute for sitting at the computer with a list of every trip you plan to do and finding out how much they are (mostly at www.sbb.ch/en) and figuring out the most cost efficient way of doing it, with a Swiss Travel Pass or a Half Fare Card. If it is close, lean to the STP for its convenience. Again, pre-purchasing the Zermatt-Venice leg now will save money, just buy the Domodossola-Venice portion at http://www.trenitalia.com/tcom-en. You can delay the decisions on the type of pass to get for Switzerland, even up to your arrival day, but the Italian portion prices will only go up as time passes.

Thanks Sam. I've spent most of the morning researching approximate costs using the Half Fare card. For the 2 of us, it's looking like a difference of a couple hundred dollars between using the Half Fare card and booking all tickets vs. getting an 8 day continuous Swiss Travel Pass. You're right - for the convenience factor of not having to worry about buying train tickets, lift tickets, museum admission, boat ride tickets, etc., that might be worth paying a couple hundred more for the Swiss Pass.

Based on our itinerary, should we leave Zermatt in the morning on 6/4, which would put us in Venice in the late afternoon/early evening? Or spend a couple extra hours in Zermatt just in case the Matterhorn decides to be stingy during our stay there? That would definitely put us in Venice later in the evening though.